It is known in the art that tetrahydrofuran may be produced by a number of different methods, the more prominent among them the dehydration of 1,4-butanediol and the catalytic hydrogenation of furan. Most tetrahydrofuran is, in fact, manufactured in a multi-step sequence starting with the reaction of acetylene and formaldehyde in the presence of a cuprous acetylide complex to form butynediol. The butynediol is hydrogenated to butanediol, which is dehydrated to tetrahydrofuran as indicated above.
In addition, tetrahydrofuran can be prepared by catalytic hydrogenation of maleic, fumaric and succinic acids, their respective anhydrides and ester derivatives, and butyrolactone.
All of these methods involve the use of hazardous or expensive materials, and catalysts that are expensive in some instances and easily poisoned in others.
The liquid phase conversion of 1,4-butanediol carboxylate ester derivatives to tetrahydrofuran in the presence of strongly acidic catalysts and water has been described by Kohll in British Patent 1,170,222 and by Ono et al in German Offenlengungsschrift 2,062,950. These processes are characterized by low rates and extent of conversion and are not suitable for use under substantially anhydrous conditions.
Tetrahydrofuran is a useful solvent for natural and synthetic resins and is a valuable intermediate in manufacture of a number of chemicals and plastics.